The present invention relates to a lens barrel operating mechanism which is capable of switching the mode set on a lens barrel, for example, by operating an operating member moving in the optical axial direction.
Applicant invented an electrically operated zoom lens provided with a lens barrel provided with a zooming operation ring which can be operated for moving the lens in the optical axial direction and filed Japanese Patent applications No. HEI 2-28902 and No. HEI 2-28903 on the invented electrically operated zoom lens on Feb. 8, 1990. Then, claiming the rights to the priority of the invention for patents, Applicant also filed a U.S. patent application as U.S. Ser. No. 651,555 in the United States on Feb. 6, 1991, now U.S. Pat. No. 5,148,199, a German patent application No. P4 103 187.1 in Germany on Feb. 8, 1991, a U.K. patent application No. 9102621.1 in the United Kingdom of Great Britain on Feb. 7, 1991, and then a French patent application No. 90 01458 in France on Feb. 8, 1991.
The electrically operated zoom lens disclosed in these patent applications is constructed in such a manner that it is capable of changing its operating modes between an electrical zooming mode, in which the focal length of the lens is changed by a built-in driving motor, and a manual zooming mode, in which the focal length is changed by the photographer's manual operation. Changing the zooming operation between these modes is performed by moving the zooming operation ring in the optical axial direction. The zooming operation ring is provided with clicking mechanisms respectively for the positions in the electrical zooming operation and the positions in the manual zooming operation, in order to enable the photographer to gain a clear and definite recognition of each of the electrically operated zooming positions defining the electrical zooming mode and each of the manually operated zooming positions defining the manual zooming mode and in order also to keep the zooming operation ring set in engagement in the current position to which the zooming operation ring has been brought.
In this regard, each clicking mechanism is provided with a pair of annular V-shaped grooves respectively formed in positions on the inner circumferential surface of the zooming operation ring in correspondence with the positions for the electrical zooming operation and with the positions for the manual zooming operation. Also, click balls, which are selectively isertable into these V-shaped grooves, and plate springs, which exert pressing force onto these click balls towards the inner circumferential surface of the zooming operation ring, are supported on the outer circumferential surface of a stationary ring. The stationary ring supports the zooming operation ring in a manner enabling it to rotate.
In the existing clicking mechanism, however, the click balls are pushed by the plate spring for their outward motion in the radial direction of the zooming operation ring. Consequently, the click balls are always held by elastic contact directly with the surface of the inner circumference of the zooming operation ring. As the result, the elastic contact of the click balls presents the problem in that their elastic contact places a load on the zooming operation ring in its linear movement and causes an undesirable sensation in its operation.